Electric welding machine



July 12, 1927. 1,635,582

I J. W. MEADOWCROFT ELECTRIC WELDING momma Filed aunso. 192s INVENTOR. Tar /{110% I wcxorr Patented July 12, 1927.

UNITED STATES 1,635,582 PATENT OFFICE.

JOSEPH W. KEADOWCBJOFT, OI PHILADELPHIA, PENNSYLVANIA, .ASSIGIOB 1'0 ID- WABD G. BUDD KANUFACTUBING COIYANY, OI PHILADELPHIA, mxmvma,

A CORPORATION 01 PENNSYLVANIA.

unc'rmc WELDING maonmn.

Application fled June 30,

My invention relatesto improvements in electric weldin machines and has to do, more particular y, with that type of electric welding machine known as a spot-welding machine, a. I r

The principal object of my present invention is to provide improvements in electric spot-welding machines by means of which a urality of different electrodes may be used in the same machine, selectively, according to the character of the work to be welded. It is customary to use a straight electrode for most welding operations but it sometimes ha ens that the shape of the pieces to be we? ed together is such that the points, at which the welds are to be made, are not accessible to straight electrodes and it is, therefore, necessary to use an electrode which is offset or of some other shape, such as to permit the positioning of the pieces to be welded in proper relation with respect to the electrode. In manufacturing operations where a large number of welds are to be made, upon pieces of many different shapes, it has been necessary, heretofore, when the operator wished to weld two pieces of metal together at points which required an offset electrode, or an electrode of some other peculiar shape, either to change the set up of the machine by substituting the offset electrode for the straight electrode, or to make these welds on a special machine equipped with such ofiset electrode. The first course requires considerable time and labor. The latter course requires the transfer of the work from one machine to the other. The object of my present invention is to rovide an electric welding machine in whic anyone of several types of electrodes may be used and in which the operator may shift from the one tyge of electrode to the other, when required to 0 so by the character of the work, very quickly and easily.

Further objects, and objects relating to details and economies of construction and operation, will definitely a pear from the detailed. description to ollow. In one instance, I accom lish the objects of my invention b the evicesand means described in the fol owing specification. My invention is clearly defined and pointed out in the appended claims. A structure constituting a I referred embodiment of my invention is illustrated in the accompanying drawings,

1928. Serial No. 848,880.

forming a part of this specification, in which:

Fig. 1 is a view in side elevation of ar electric welding machine embodying my invention.

Fig. 2 is a fra mentary view, corresponding to a part of ig. 1, but showing the electrode carrier shifted to bring another of its electrodes into operative position.

Fig.3 1s a fragmentary, plan view of the fixed arm of the welding machine, taken on the line 3 -3 of Fig. 1.

Fig. 4 is a detail, sectional view, taken on the line of Fig. 1, and

F1 5 is a detail, sectional view, taken on the line 55 of Fig. 4.

In the drawings, the same reference numerals refer to the same parts throughout the several views and the sectional views are taken looking in the direction of the arrows at the ends of the section lines.

The ordinary spot welding machine cons sts of two electrodes connected to opposite sides of a source of welding current such as a transformer, and means for reciprocating one of these electrodes with respect to the other, so as to bring them into contact, under pressure, with opposite sides of the pieces to be welded together, with the result that the welding current flows from one electrode to the other, through the pieces to be welded, at the spot of contact. My invention consists, in substituting for one of these electrodes a plurality of electrodes connected to the same side of the source of welding current and shiftable laterally so that any one of said electrodes may be moved into position to cooperate with the electrode which is connected to the opposite side of the source of welding current. These shiftable electrodes may very well be different in size or shape, so that they are suited to work of different character, thus extending the operative range of the machine. I propose to mount a shlftable carrieron the fixed arm of the welding machine which is connected to one side of the source of welding current and carries a lurality of electrodes, so that, by shifting this carrier, any one of Said electrodes may be brought into 0 e-rative posi tion, These electrodes may e connected with a suitable cooling system and I find it desirable to connect themin series so that the cooling fluid flows from one electrode to the other, as it flows through the system. I may use, in connection with such a shiftable carrier having a plurality of electrodes, 9.

electrode of the ordinary type may be used,

without departing from the spirit of my invention.

Referring to the numbered parts of the drawings, in which there is illustrated a spot welding machine constituting one embodiment of my invention, the frame, 10, of the machine is provided with an upper arm, 12, and a lower arm, 11. A plunger, 13, is mounted at the end of the arm, 12, so that it may be reciprocated by the lever. 14. The lower end of the plunger, 13, carries a bar, 16, which is connected by the lead, 15, with one side of a welding transformer, not shown. The 'opposite side of said transformer is connected to the lower, fixed arm, 11, which arm is of good conducting material, such as copper. A channel bar, 17. is secured to the lower face of the bar. 16, and forms a guide-way in which the block, 19, is slidable, said block being retained in the guide-way by the plates, 18, which are fastened to the lower surface of the channel, 17, and overhang the guide-way, as shown in Fig. 4. An electrode, 20, is carried by the block, 19, and extends downwardly through the slot or space between the adjacent edges of the plates, 18. The electrode, 20, is hollowed out after the usual manner, so as to receive cooling fluid from a coolin system, to which the interior of said electro e 1s connected by the conduits, 21 and 22.

At the outer end of the lower, fixed arm, 11, there is provided a lane surface, 37, on which rests an electro e carrier, 23. This electrode carrier, in this instance, is in the form of a bell-crank, having the arms, 24 and 25, and pivotally connected to the arm, 11, by the bolt, 26. This bolt extends through the bell-crank, 23, and through the end of the arm, 11, and extends downwardly some distance below the latter, as shown in Figs. 1 and 2. A spring, 27, is interposed between the head, 29, of said bolt and the lower surface of the arm, 11. This spring, therefore, yieldingly holds the bell-crank, 23, in intimate contact with the surface, 37, of the arm, 11, so as to maintain good electrical contact between these two parts. The bell-crank, 23, has an arcuate slot, 30, in which is dis osed the pin, 31, carried by the arm, 11. is device serves to limit the swinging movement of the bell-crank or elec trode carrier about the bolt. 26. At the outer end of the arm, 24, of the carrier, the electrode, 33, is mounted and the electrode,

32, is mounted at the outer end of the arm, 25. I have shown the electrode, 32, as a straight electrode of the usual ty e, while the electrode, 33, is offset. The e ectrodes, 32 and 33, are connected in series in the cooling system, by the conduits, 34, 35 and 36, so that the cooling fluid flows into one of these electrodes, from it into the other electrode, and thence to the point of discharge.

In Figs. 1 and 2, the pieces of metal to be welded together are illustrated in section. In Fig. 1 an angle member, B, is to be welded to a flange at the 11 per edge of the panel, A. In work of this 0 aracter, it is possible to use a straight electrode because the work is so shaped that the pieces can be positioned between the cooperating electrodes without difiiculty. In Fig. 2,'an angle member, B, is to be welded to a flange at the upper edge of a panel, C, which has an offset or channel formation at its 11 per edge. This offset would interfere wit 1 the use of a straight electrode, such as the electrode, 32, and, therefore, an offset electrode, 33, is used. It often happens that the same stam ing would have parts formed, as at A, (see ig. 1) and other parts formed as at C, (see Fig. 2) and, with my improved welding machine, welds can be made at both places without removing the work from the machine. It will be seen that the carrier, 23, may be swung very readily on its pivot, 26, so as to substitute the offset electrode, 33, for the straight electrode, 32, or vice versa. In case it is necessary, the upper electrode, 20, may also be shifted laterally, so as to bring it into precise alignment with the lower electrode, with which it is to cooperate. The welding is accomplished in the usual manner by reciprocating the plunger, 13, so as to bring the upper electrode into contact with the upper surface of the ieces to be welded together in alignment with that one of the electrodes carried by the shiftable carrier'which has been brought into operative osition by the movement of the carrier. The welding current flows from the transformer, through the electrode, 20, the pieces to be welded together, the lower electrode, the electrode carrier, 23, and the arm, 11, to the opposite side of. the transformer, thus makin a weld at the spot at which the upper an lower electrodes contact with the pieces to be welded to ether.

am aware that the electric weldin machine illustrated in the accom anying rawing may bealtered considerab y, without departing from the spirit of my invention, and, therefore, I claim my invention broadly, as indicated by the a pended claims.

Having thus d'escri ed my invention, what I claim as new and useful and desire to secure by Letters Patent is:

1. In an electric welding machine, the

- c'iprocatingsaid plunger.

2. In an electric welding machine, the combination of a frame having a relatively fixedarm, a reciprocable plunger carried'by said frame, an electrode carried by said plunger and connected to one side of a source of welding current, a bell-crank pivoted on said fixed arm, means for limiting the swinging movement of said bell-crank, an electrode mounted at the end of each bell-crank arm and connected to the opposite side of said source of current, said bell-crank swinging about its pivot to bring any one of its electrodes into cooperative relationship with the first-mentioned electrode, and means for.

reciprocating said plunger. v i

3. In an electric welding machlne, the combination of a frame having a relatively fixed arm, a reciprocable plunger carried by said frame, an electrode carried by said plunger and connected to one side of a source of welding current, an electrode oarrier pivotally mounted on said fixed arm, spring means yieldingly holding said carrier in contact with said arm to maintain electrical contact between such parts, a plurality of electrodes carried bysaid carrier and connected to'the opposite side of said 7 source, said carrier swinging about its pivot to bring any one of its electrodesinto cooperative relationship with the first-mew tioned electrode, and means for reciprocating said plunger.

4. In an electric welding machine, the combination of a frame having a relatively fixed arm, a reciprocable plunger carried by said frame, an electrode carried by said plunger and connected to one side of a source of welding current, an electrode carrier, abolt extending through said carrier and said arm and constituting the pivot for said carrier, a spring surrounding said bolt and interposed between the. head of said bolt and said arm to maintain said arm and carrier in intimate contact, a plurality of electrodes carried by said carrier and connected to the opposite side of said source, said carrier swinging about its pivot to bring any one of its electrodes into cooperative relationship with the first-mentioned electrode, and means for reciprocating said plunger.

5. In an electric welding machine, the combination of a frame, a reciprocable plunger carried by said frame, a relatively fixedarm carried by said frame, a laterally shiftable electrode carried by said plunger and connected to one side of a source of welding current, a plurality of electrodes connected to the opposite side of said source of current and carried by said fixed arm, said last-mentioned electrodes being shiftable to bring any one of them into cooperative relationship with the electrode carried by said plunger and to remove any of the others from cooperative relationship therewith, and means for reciprocating said plun er.

6. In an electric welding machine, the combination of a frame, a reciprocable plunger carried by said frame, a relatively fixed arm carried by said frame, a laterally shiftable electrode carried by said plunger and connected to one side of a. source of welding current, a carrier pivotall mounted on the end of said fixed arm, a p urality of electrodesconnected to the opposite side of said source of current and carried by said carrier, said carrier being shiftable to bring any one of said last-mentioned electrodes into cooperative relationship with theelectrode carried by said plunger, and means for reciprocating said plunger.

7. In an electric welding machine, a reciprocable electrode connected to one side of a source of welding current, a plurality of cooperating electrodes having relatively displaced welding positions, and connected to the other side of said current's'ource, said electrodes being laterally shiftable to bring them into aligned relation intheir welding positions, and means to reciprocate said reciprocable electrode.

8. In an electric welding machine, the combination of a frame, a reciprocable plunger carried by said frame, an electrode carried by said lunger and shiftable laterally independent y thereof, a relatively fixed arm'carried b said frame, a plurality of electrodes carried by said fixed arm adapted to be selectively brought into 'coo lationship with said first name electrode.

9. In an electric welding machine, the combination of a frame, a reciprocable plunger carried by said frame, an electrode carried by said plunger and shiftable laterally independently thereof, means for reciprocating said plunger, a relatively fixed arm carried by said frame, a plurality of electrodes carried by said fixed arm adapted to be selectively brought into cooperative relationship with said first named electrodes, and conduits connecting the electrodes on the fixed arm in series with a cooling medium.

rative re-.

In testimony whereof, I aflix my signature. 

